A fuse is usually installed as a protective device in electrical systems. It protects electrical systems from short circuit and overloads. It operates by interrupting the current by evaporation or melting of a conductive material, thereby interrupting an arc.
Usually the fuses are installed in environments with 1 atmosphere pressure. Fuses can generally not withstand the increased external pressure present in subsea applications. Subsea installations may today be located at depths of up to 3000 meters. At such depths the ambient pressure is 300 bar, and such pressure may result in mechanical damage and unexpected behaviour of a fuse.
Typically in subsea applications fuses have been installed inside an oil-filled enclosure containing a particular electrical device such as a transformer or a power converter. These fuses shared the same oil volume as the electrical device, which could lead to oil contamination. Moreover, arc interrupting capabilities are dependent of the insulating medium and on the ambient pressure. Therefore for each installation depth the fuses could have different behaviour.
These problems have been addressed in for example EP2565899 which discloses a pressure resistant housing for an electric component. This document discloses a pressure resistant housing adapted for the use in a subsea application. A ceramic housing body houses the electric component. The ceramic housing body has a first opening and a second opening which are closed by a first metal lid and a second metal lid, respectively.
One disadvantage with this design is that it requires a rather complex manufacturing process which includes metallization of the edges of the openings of the ceramic housing body and soldering with the metal lids.